1. Field of the Invention
The present invention relates to an input device for shifting a marker on a monitor of the type used for program control or for system control via graphic user surfaces.
2. Description of the Prior Art
German OS 43 16 888 discloses an input device of the above general type which is called an "optical mouse". The optical mouse has the shape of a small housing in which an optical scanning system is arranged. The optical scanning system detects the movements in two perpendicular coordinate directions which the mouse executes on a movement base overlaid with a grid of points or lines. Each point or line which is overrun by the optical mouse causes an optical signal to be generated that is converted into a corresponding electrical signal by opto-electronic converters, with the marker on the monitor--generally a cursor--being shifted in position on the basis of the electrical signal. At least one electrical button is generally arranged on the mouse for entering commands that usually serve to initiate functions connected to the position or the path of the cursor on the monitor. The mouse is connected to a separately arranged evaluation unit via optically conductive fibers exclusively. The optically conductive fibers transmit the optical signals from the optical scanning system to the evaluation unit. Since the detection of the relative motion of the two parts with respect to one another occurs purely optically and is emitted as an optical signal via optically conductive fibers, disturbing electric or magnetic influences from the operating system are precluded. Disturbing electrical or magnetic signals that may disturb the operation of the connected computer likewise cannot be picked up. A drawback, however, is that due to the optically conductive fibers the mouse cannot be operated in the sterile working environment of a surgeon.
German OS 44 41 169 also discloses an input device having a housing in which motion detectors are arranged along with an evaluation and protocol circuit connected thereto. The housing contains an electrical shield within which motion detectors and the evaluation and protocol circuit are arranged, along with an electro-optical conversion unit connected to the latter. The electro-optical conversion unit converts the electrical signals emitted by the evaluation and protocol circuit into corresponding optical signals. A lead-through filter is arranged in the shield through which the evaluation and protocol circuit can be powered with electrical energy. An opening is further arranged in the shield through which the fiber-optical transmission means (light waveguides) connected to the electro-optical conversion unit are led out of the shield. By means of the transmission of the control signals via a light waveguide it is guaranteed that an undisturbed data transmission to a connected computer is possible even in high-frequency electromagnetic fields. A disturbance by the input device itself is also thereby precluded. Operation in the sterile working environment of a surgeon, however, is not possible in this case, either.
German OS 30 36 217 describes a stationary input device which operates a medical device disposed at a distance from the input device can be operated. The input device contains a transmitter for the wireless transmission of control commands to the medical device being controlled, a switch arrangement for controlling the transmitter dependent on the operating elements of the input device, and an energy storage unit (battery). The input device can be surrounded by a sterilizeable jacket or shell that is permeable at the frequency of the transmitter.